Summary:

The purpose of the study was to determine of influence of irrigation and ni-trogen fertilization on the amount of losses after the storage of early potato culti-vars during 6 months. Investigations were carried out in 2005–2007 in Kruszyn Krajeński near Bydgoszcz on the soil included to the weak rye complex of agricultural suitability. The experiment was conducted as 3-factorial trial, with three rep-lications. The first row factor was early potato cultivar: ‘Dorota’, ‘Gracja’. The second row factor was sprinkler irrigation applied in two variants: W_o – without irrigation (control), (kontrola), W₁ – sprinkler irrigation according to indications of tensiometers (irrigation was started when the soil water potential achieved -0,03 MPa). The three row factor was differentiated nitrogen fertilization: N₀ = 0 kg N•ha ^-1, N₁ = 40 kg N•ha ^-1, N₂ = 80 kg N•ha ^-1, N₃ = 120 kg N•ha ^-1. The studied cultivars were characterized by differentiated susceptibility to losses total during the storage. cv. ‘Dorota’ was characterized by the higher losses during the long storage. Irrigation during the vegetation period increased in tubers the amount of natural losses, decrements and the losses caused by sprouting. Nitrogen fertilization of the higher doses as well as in control variants caused the increase of natural losses and decrements in the studied cultivars. Agrometeorological con-ditions during the vegetation of potato influenced distinctly the amount of losses during the storage of tubers. Higher losses were noted in the years characterized by the higher rainfall amounts.